This invention relates to apparatus for dispensing a fine spray of liquid particles and more especially to liquid dispensing apparatus known as air brushes.
Conventional air brushes comprise a liquid store connected to receive high pressure gas from a source. The high pressure gas passes over the liquid store to produce a spray of liquid particles which is directed by a nozzle onto an appropriate surface. The pressurised gas from the source is supplied to the air brush via a conduit and its flow is controlled by a manually operated or automatically controlled valve. Typically the pressurised gas source includes propellant and is contained in a heavy metal cylinder. JP-A-61042350 and UK 2177620A disclose such an air brush in which the liquid store takes the form of a felt-tipped pen.
My British Patent 2245196 and International Patent Application PCT/GB93/02332 disclose air brush apparatus for dispensing fine sprays of liquid particles. These air brushes comprise a hand or foot operated pump connected to supply air under pressure directly to a nozzle so positioned that air leaving the nozzle is directed onto and over a nib of a felt-tipped pen realisably supported within a holder with the absorbent nib of the pen in close proximity to the nozzle outlet to cause liquid from the nib to be dispensed as a fine particulate spray in air.
An airbrush including a cylindrical housing formed with a mouthpiece for use with a felt-tipped pen is disclosed in published British Patent Application 2257058. The pen disclosed in this application is of special design and includes an end cap formed with a hole to equalise the pressure within the pen reservoir to avoid the presence of a vacuum.
An improved tubular construction of air brush dispenser is disclosed in my International Patent Application PCT/GB94/00595. This dispenser comprises a hollow tubular housing and a felt-tipped pen which is retained within and spaced from the inner wall of the housing. The tubular housing includes at one end a nozzle and at its other end a mouth piece through which air can be caused to flow through the tubular housing and over the pen to the outlet orifice of the nozzle. An abutment is provided within the housing for locating the pen within the housing with its absorbent nib at least partially within the boundary of the outlet orifice of the nozzle.
A further and improved dispenser is disclosed in my co-pending British Patent Application 9514671.8 which, as for my earlier Application PCT/GB94/00595, removes the need for a pump but which, by a blowing action, causes the required fine spray of coloured particles to be removed from a liquid store such as an absorbent nib of a pen containing a colorant, ink, paint or the like. The air brush dispenser of my later application is an improvement over my earlier design in that it provides a simple and very secure means for locating a pen or cartridge within the tubular casing and has an outlet nozzle whose profile optimises the flow of air around the nib of the pen or other liquid source thereby enabling even young children to operate the dispenser to achieve colouring effects normally associated with much more expensive and complicated equipment.
The present invention sets out to provide alternative dispensers to those disclosed in my earlier application.